Magic Mouse, right clicking does not work

Boot into Safe Mode according to Start up your Mac in safe mode - Apple Support and see if the problem persists. Reboot normally and check again.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

If it still persists after the normal reboot log into another vanilla admin user account, Set up users, guests, and groups on Mac,  and see if the problem persists. This tells us if the problem is limited to your user account or is system wide.

Try to reinstall macOS: How to reinstall macOS - Apple Support. This will not delete anything, but is a good idea to have a proper backup first.

Cheers,

Jack

Hi TouchCAD,

So, just to confirm, you've gone to System Preferences --> Mouse --> Point & Click --> Secondary click, and in the dropdown right below select "Click on right side"?

Cheers,

Jack

Did the secondary click ever work since the Samsung SSD?